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authorJohannes Berg <johannes@sipsolutions.net>2009-04-16 13:17:26 +0200
committerJohn W. Linville <linville@tuxdriver.com>2009-04-22 16:57:16 -0400
commitd91f36db51661018f6d54ff5966e283bcec4c545 (patch)
treecde91cde0e6478c3c8cb256786eb61f3c48842c4 /net/mac80211/util.c
parent10f644a47b76d3e61b98f2d02ce9690b94c51ee5 (diff)
downloadlinux-d91f36db51661018f6d54ff5966e283bcec4c545.tar.bz2
mac80211: implement beacon filtering in software
Regardless of whether the hardware implements beacon filtering, there's no need to process all beacons in software all the time throughout the stack (mac80211 does a lot, then cfg80211, then in the future possibly userspace). This patch implements the "best possible" beacon filtering in mac80211. "Best possible" means that it can look for changes in all requested information elements, and distinguish vendor IEs by their OUI. In the future, we will add nl80211 API for userspace to request information elements and vendor IE OUIs to watch -- drivers can then implement the best they can do while software implements it fully. It is unclear whether or not this actually saves CPU time, but the data is all in the cache already so it should be fairly cheap. The additional _testing_, however, has great benefit; Without this, and on hardware that doesn't implement beacon filtering, wrong assumptions about, for example, scan result updates could quickly creep into code. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/mac80211/util.c')
-rw-r--r--net/mac80211/util.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index b361e2acfce9..3dd490fa4b68 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -20,6 +20,7 @@
#include <linux/if_arp.h>
#include <linux/wireless.h>
#include <linux/bitmap.h>
+#include <linux/crc32.h>
#include <net/net_namespace.h>
#include <net/cfg80211.h>
#include <net/rtnetlink.h>
@@ -537,8 +538,16 @@ EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces_atomic);
void ieee802_11_parse_elems(u8 *start, size_t len,
struct ieee802_11_elems *elems)
{
+ ieee802_11_parse_elems_crc(start, len, elems, 0, 0);
+}
+
+u32 ieee802_11_parse_elems_crc(u8 *start, size_t len,
+ struct ieee802_11_elems *elems,
+ u64 filter, u32 crc)
+{
size_t left = len;
u8 *pos = start;
+ bool calc_crc = filter != 0;
memset(elems, 0, sizeof(*elems));
elems->ie_start = start;
@@ -552,7 +561,10 @@ void ieee802_11_parse_elems(u8 *start, size_t len,
left -= 2;
if (elen > left)
- return;
+ break;
+
+ if (calc_crc && id < 64 && (filter & BIT(id)))
+ crc = crc32_be(crc, pos - 2, elen + 2);
switch (id) {
case WLAN_EID_SSID:
@@ -587,15 +599,20 @@ void ieee802_11_parse_elems(u8 *start, size_t len,
elems->challenge = pos;
elems->challenge_len = elen;
break;
- case WLAN_EID_WPA:
+ case WLAN_EID_VENDOR_SPECIFIC:
if (elen >= 4 && pos[0] == 0x00 && pos[1] == 0x50 &&
pos[2] == 0xf2) {
/* Microsoft OUI (00:50:F2) */
+
+ if (calc_crc)
+ crc = crc32_be(crc, pos - 2, elen + 2);
+
if (pos[3] == 1) {
/* OUI Type 1 - WPA IE */
elems->wpa = pos;
elems->wpa_len = elen;
} else if (elen >= 5 && pos[3] == 2) {
+ /* OUI Type 2 - WMM IE */
if (pos[4] == 0) {
elems->wmm_info = pos;
elems->wmm_info_len = elen;
@@ -680,6 +697,8 @@ void ieee802_11_parse_elems(u8 *start, size_t len,
left -= elen;
pos += elen;
}
+
+ return crc;
}
void ieee80211_set_wmm_default(struct ieee80211_sub_if_data *sdata)